The Molecular Screening Shared Resource (MSSR): Completion of the genome sequences of humans, mice, zebrafish and a number of other model organisms has led to the tentative identification of all encoded proteins in these species. The proliferation both of chemical libraries and of libraries of genome wide inhibitory RNA sequences for a number of species has made it possible to conceive of looking for inhibitory small molecules and inhibitory RNAs for all genetically encoded targets. The concomitant development of High Throughput Screening (NTS) technologies has made it possible - with the right resources - to move this from concept to practice. The UCLA JCCC Molecular Screening Shared Resource (MSSR) was established in 2003 to meet this exciting scientific objective. The MSSR now has dedicated space in the new California NanoSystems Institute, small molecule libraries containing over 70,000 compounds, genomewide knockout libraries for yeast, and interfering RNA libraries for both murine and human targets. Excellent academic and technical leadership has established a robust, accessible screening center that assists both in developing reliable and robust enzymatic and cell culture HTS assays and in facilitating genome-wide screens. The David Geffen School of Medicine, the California NanoSystems Institute (CNSI), the UCLA College of Letters and Science, several individual departments and some private donors have joined the JCCC to provide funding for the equipment and libraries (well over $1,000,000) and operating "start-up" required to get the MSSR up and running. The Shared Resource has run (or is currently running) 65 screens, the great majority of which are for JCCC members. Members of the Gene Regulation, Signal Transduction and Therapeutics, Tumor Immunology, Cancer Cell Biology, Hematopoietic Malignancies, Developing Program in Molecular Epidemiology and Carcinogenesis, Thoracic Oncology and Genitourinary Oncology Program Areas have already utilized this Shared Resource. The CCSG budget request for this Shared Resource for the first year CCSG budget is for 13% of the estimated operating budget;support for the shared resource also comes from the CNSI, an NIH Center for Radioprotectors, the UCLA Chancellor's Biosciences Initiative, user recharges and philanthropy. (Please also see Section 6.2.3 on Shared Resources in the History, Description, Essential Characteristics). Eight Cancer Center members representing four Cancer Center Program Areas completed screens in the Molecular Screening Shared Resource during the reporting period;many screens are ongoing. This is a continuing shared resource.